Sea surface temperature (SST)

Sea surface temperature is the temperature of ocean water in the uppermost few millimeters to meters, measured by satellite infrared and microwave radiometers, moored and drifting buoys, ships, and autonomous floats. It is one of the most widely used ocean variables because it strongly influences the atmosphere above it.

Satellite remote sensing provides near-global daily coverage but must be corrected for cloud contamination, and infrared sensors read only the very top of the water column, so it is often blended with in-situ buoy measurements into gridded analysis products. This differs from ocean color remote sensing, which measures light reflected by chlorophyll and sediment rather than temperature, though both are typically produced by the same class of satellite instruments.

SST is a primary input to numerical weather prediction and seasonal forecast models, since it drives hurricane intensification, monsoon behavior and El Niño-Southern Oscillation cycles, and long SST records built from reanalysis data are central to detecting ocean warming trends. A common pitfall is comparing SST values from different sensors or depths without adjusting for their different measurement methods, since satellite "skin" temperature and buoy "bulk" temperature can differ by a fraction of a degree in ways that matter for precise trend analysis.